The present invention relates to the image reconstruction arts. It finds particular application in conjunction with convolution/backprojection reconstruction of CT image data and will be described with particular reference thereto. It is to be appreciated, however, that the invention will also find application in conjunction with other reconstruction processes in which data is backprojected or subject to processing techniques analogous to backprojecting, such as SPECT imaging.
Heretofore, CT image data from the detectors has been convolved, often several lines in parallel for faster processing. The convolved data is backprojected into an image memory to create an image representation. In order to improve resolution, the convolved data has been subject to linear interpolation prior to backprojection. In a typical linear interpolation, adjacent data lines are averaged. However, linear interpolation tends to create Moire artifacts.
The Moire artifacts can be reduced or eliminated by using higher order interpolations. That is, rather than a simple linear averaging of nearest neighbor data lines, a more complicated averaging of several neighboring as well as the nearest neighboring data lines. The problem with higher order interpolations is that they have heretofore required additional memories to accommodate the larger plurality of neighboring data lines combined in the higher order interpolation.
The present invention contemplates a new and improved higher order interpolation which overcomes the above-referenced problems and others.